Nonlinear panel-data models

What's this about?

Stata now fits nonlinear models with random effects. This means that when
your science says that the model should be nonlinear in the parameters,
as in the constant elasticity of substitution (CES) production function or
in a growth curve for adoption of a new technology, you can now fit that model
even when you have panel data. Parameters in the fixed portion of the model
and random effects can both enter the model nonlinearly.

Now instead of fitting a linear model with random effects \(U_j\), such as